Re: Checksum error and VACUUM FULL

On Thu, Aug 25, 2016 at 5:45 AM, Tatsuki Kadomoto <
tatsuki(dot)kadomoto(at)proceranetworks(dot)com> wrote:

> I faced incorrect checksum on "global/pg_filenode.map" at the right
> timing "VACUUM FULL" is executed and session was aborted.
>
> Aug 16 20:51:19 postgres[22329]: [2-1] FATAL: relation mapping file "global/pg_filenode.map" contains incorrect checksum
>
> Aug 16 20:51:19 postgres[22329]: [2-2] STATEMENT: SELECT id,readbm,writebm,survbm,timeout FROM Users WHERE username='packetlogicd' AND password=md5('xxxxx')
>
> I'm reading the comment in src/backend/utils/cache/relmapper.c .
>
> ===
> Therefore mapped catalogs can only be relocated by operations such as
> VACUUM FULL and CLUSTER, which make no transactionally-significant changes:
> it must be safe for the new file to replace the old, even if the
> transaction itself aborts.
> ===
>
> Does this comment mean it's expected to get this kind of checksum error if
> the timing is really bad?
>

I don't think so.

--
Robert Haas
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